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PRELIMINARY; Be sure all tubes are firmly seated in their
sockets and that the tube shields are making good contact
with their bases. As initial adjustments, set these controls
as follows; LEVEL at zero, LOUDNESS at ten, BASS at
zero. Turn the amplifier on by turning the TREBLE control
clockwise from OFF and set it at zero initially. Note that
the LEVEL, LOUDNESS, BASS and TREBLE controls have
no effect on the TAPE OUTPUT.
LISTENING TO PHONOGRAPH; Set the SELECTOR to
one of the record equalization positions on the dial. Do-
ing so automatically selects the phonograph input plugged
into the PHONO LO or PHONO HI input. For help in
choosing the recording curve appropriate to any parti-
cular record, refer to the chart titled "RECORD EQUALl*
ZATION SELECTION" ,When in doubt as to which equali-
zation is most appropriate, use RIAA, which is the best
compromise for all records. Keep in mind that while the
positions offered cover most recording curves likely to be
encountered, additional separate and variable bass and
treble response adjustments are necessary for fully satis-
factory results. These may be necessary to compensate
for the over-all characteristics of ydur audio system (in-
cluding room acoustics), inexact matching of the actual
recording characteristic by any of the equalizations pro-
vided, and above all, the particular tastes of the listener.
LEVEL &LOUDNESS CONTROLS: Simply stated, the
purpose of the LOUDNESS control is to provide compen-
sation for the increasing inefficiency of the human ear In
hearing bass and treble with decreasing volume level. The
LOUDNESS control, as it is turned counter“clockwise from
maximum clockwise rotation, not only decreases the volume
but increasingly emphasizes the bass and treble according
to the Fletcher-Munson curves (curves developed from a
statistical study of this effect). An uncompensated LEVEL
control is also provided to "set" the LOUDNESS control
for proper operation In any system, and also for the purpose
of adjusting the listening level when going from quiet pro-
gram material to loud program material or the reverse with-
out occasioning achange In the loudness compensation .
To "set" the LOUDNESS control at anytime, perform these
operations in the order given to avoid blasting or possible
damage to speakers of low power-handling capacity; a)
Turn the LEVEL control to zero; b) Turn the LOUDNESS
control to ten; c) With high level orchestral program
material being fed to the amplifier from your phonograph
or tuner, advance the LEVEL control setting until a rela-
tively loud listening level Is obtained, d) Turn down the
LOUDNESS control until your normal listening level is ob-
tained with the LEVEL control set as just described. Proper
loudness compensation should now be obtained at any list-
ening level adjusted to with the LOUDNESS control. The
same reference LEVEL control setting will be suitable for
both phonograph and tuner listening If the volume control
of the tuner has been odjusted as described In the "High
Level Inputs" sub-section of the "Electrical Connections"
section. When selecting inputs which do not have level
adjusts, such as tv or acrystal cartridge connected to the
AUX. input, it may be desirable to set the LEVEL control
to zero beforehand and then bring up the LEVEL control to
obtain the desired listening level to avoid blasting
BASS CONTROL; The plus sign on the right side of the
dial indicates that clockwise rotation from the mid-point
(0) increases (boosts) bass response; the minus sign on the
left side indicate that counter-clockwise rotation from the
mid-point decreases (cuts) bass response. There Is no in-
teraction with the TREBLE control. Start all adjustments
with this control set at the mid-point (0), which is called
the "flat" position since bass response Is neither cut nor
boosted at this etting.
TREBLE CONTROL; The plus i^ign on the right side of the
dial indicates that clockwise rotation from the mid-point
(0) Increases (boosts) treble response; the minus sign on
the left side indicates that counter-clockwise rotation
from the mid-point decreases (cuts) treble response. There
is no interaction with the BASS control .Start all adjust-
ments with this control set at the mid-point (0), which is
called the "flat" position since treble response is. neither
cut nor boosted at this position.
LISTENING TO TUNERS, TV, TAPE RECORDERS: With
the SELECTOR switch set qt TUNER, TV, TAPE or AUX-
ILIARY, the corresponding high level input from aradio
tuner, tv, tape recorder, second tuner or crystal cartridge
will feed through the amplifier. Adjustment of the volume
control on each source is discussed in the "Electrical Con*-
nections" section under "High Level Inputs" and again
under "Level &Loudness Control" In this section.
MAKING RECORDINGS; Tape recordings may be made
by connecting the recorder to the TAPE OUTPUT jack.
See "Tape Output" under "ELECTRICALCONNECTIONS"
,
With the output of the recorder connected to the TAPE IN"
PUT jack, turning the SELECTOR switch to TAPE readies
the amplifier for playback of the recording,
RECORD EQUALIZATION SELECTION
Records are made with boosted volume in the treble range
to mask surface noise and reduced volume in the bass range
to conserve groove space and reduce distortion. As there
was no universally accepted standard of treble boost and
bass cut in recording before Spring 1954, records of which
the masters were made before this date may require any one
of several different equalizations (amounts of bass boost
and treble cut) by the amplifier to restore the original baU
once. Thespecific equalization required depends upon the
brand of the record, and the equalization which should be
used for each record brand (for recordings made before
1954) is listed in the first column to the right of the com-
pany’s name in the chart below. In some cases, additional
adjustment is required with the BASS control to match the
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